This invention relates to sterilization of contact lenses using hydrogen peroxide as the disinfectant, and more particularly relates to improved catalytic control of the decomposition of hydrogen peroxide in the lens disinfection process.
The well-known, commercialized soft contact lens disinfection process employing hydrogen peroxide solution as a bactericide is described for example in U.S. Pat. Nos. 4,750,610; 4,013,410 and 3,912,451. Recent improvements in contact lens cases for conducting such disinfection process are described in co-pending U.S. patent application Ser. No. 364,471 filed Jun. 9, 1989 which is incorporated by reference herein. In such process, the contact lenses are immersed overnight in a weak bactericidal solution of hydrogen peroxide which is also subjected to platinum catalyst to promote gradual decomposition of the hydrogen peroxide since significant hydrogen peroxide residues upon contact lenses can cause harm and irritation to the eyes of contact lens wearers. It has generally been recommended not only to allow sufficient time for nearly complete decomposition of the hydrogen peroxide, but additionally to employ a rinsing solution to flush any potential hydrogen peroxide residues from the lenses before insertion into the eyes.
In addition to the decomposition of the hydrogen peroxide, it is also important that the lenses be exposed to the relevant maximum strength of the disinfectant solution for sufficient time to destroy the harmful bacteria. Thus, the decomposition must not be too rapid, otherwise the lenses will not be thoroughly disinfected. The decomposition process, however, must be complete after a period of time to protect the eyes. One object of the present invention is to improve the catalytic control over the hydrogen peroxide lens disinfection process, while additionally ensuring that upon completion of the lens disinfection process, the terminal hydrogen peroxide concentration is sufficiently reduced for safe contact by residues adhering to the disinfected lenses with the eyes of the wearer.